Peristaltic pumps are well-known in the art and may be defined as pumps which produce pulse-like movement to push matter through a tube.
In FIG. 1, there is shown a prior art device that was manufactured by Knight Equipment International, Inc., of Costa Mesa, Calif., now Knight, Inc. of Northbrook, Ill.
Inside a casing 10, there is a pump 12 in which a triangular rotor 14 rotates to compress a flexible rubber tube 16 against a curved wall 30 at points A and B. These points A and B change along the length of the tube 16 as the rotor 14 rotates around its central axis 18. Three pins 20 hold three rollers 22 at tips X, Y and Z of the rotor 14 while four screws 24 hold front and back portions of the casing 10 together. The tube 16 has an inlet suction branch 16C and an outlet delivery branch 16D. Arrows I and 0 indicate the direction of flow of liquid detergent into and out of the tube 16. A clear, hard plastic cover 26 with a tab 28 allows a user to view and to have access to the interior of the casing 10 in order to replace or repair any parts of the pump 12 and the rotor 14 which may break.
One disadvantage of this prior art device is that the constant vibration of an industrial washing machine in which it is used tends over time to cause the screws 24 to work loose from the casing 10, thus causing the pump 12 inside to fail. Also, the constant vibration causes the pins 20 holding the rollers 22 in the rotor 14 to work loose and push up against the cover 26 until the cover 26 pops off. Once again the pump 12 fails. Thus, it is a problem in the prior art to develop a peristaltic pump which is resistant to constant vibrations that eventually caused earlier devices to become loose and fail.
Another disadvantage is that a high-torque point may be created at the inlet end as a tip of the rotor 14 engages the tube 16 at point C. The motor (not shown) typically used to operate the rotor 14 is small and may not generate sufficient power to start the rotor 14 moving. Accordingly, if a larger powered motor is not used, the appliance may experience frequent motor burnout.
The present invention is designed to overcome these and other problems associated with prior art peristaltic pumps.